Mood disorders on genetic spectrum

February 04, 2020

Philadelphia, February 4, 2020 - Researchers shed new light on the genetic relationship between three mood disorders associated with depression--major depression and bipolar disorder types 1 and 2, in a new study in the journal Biological Psychiatry, published by Elsevier.

"The clearest findings are a genetic distinction between type 1 bipolar and type 2 bipolar, and the greater similarity of type 2 bipolar to major depressive disorder," said first author Jonathan Coleman, PhD, a statistical geneticist and postdoctoral fellow in the lab of senior author Gerome Breen, PhD at the Institute of Psychiatry, Neuroscience, and Psychology at Kings College London, UK.

Both types of bipolar disorder used to be referred to as 'manic-depressive disorder'. Mania is a behavioral state associated with behavioral activation, euphoric or irritable mood, reduced need for sleep, impulsive behavior, impaired judgement, racing disorganized thoughts, impulsive behaviors, and frequently strongly held false beliefs (delusions) or hallucinations. Bipolar disorder type 1 is associated with mania and depression, while bipolar 2 is predominately associated with depression marked by mild symptoms reminiscent of mania, called hypomania.

The insights came from several extremely large datasets analyzed together. For their meta-analysis, Coleman, Breen and their co-authors combined genome-wide association studies from three large datasets of people with major depression and bipolar disorder to evaluate shared and distinct molecular genetic associations. Most of the data came from the large international Psychiatric Genomics Consortium. Additional data came from the UK Biobank, a major health resource established by the Wellcome Trust, and the online genetic service platform, 23andMe.

There are significant racial and ethnic differences in the findings from genome-wide association studies (GWAS). The findings of this study pertain only to people of European ancestry and findings might be different in other groups.

The authors also report that the genetic risk for these disorders was predictive of other traits as well. For example, the genetic risk for bipolar disorder was correlated with more educational attainment, while the heritable risk for major depressive disorder was associated with less education.

In the mouse brain, the authors also mapped the genetic risk for these disorders on to particular brain cell types using a sophisticated analytic strategy building on the pattern of genes expressed. They implicated serotonin neurons in the risk for both depression and bipolar disorder, while bipolar disorder distinctively involved GABA and glutamate neurons (nerve cell types also implicated in schizophrenia).

"We have long known that mood disorders are highly heterogeneous and the boundaries between types of mood disorders are often difficult to define clinically," said John Krystal, MD, editor of Biological Psychiatry. "This new study suggests that there are aspects of genetic risk, and presumably brain function, that link forms of mood disorders, but there are also distinctions that may shed light on subtypes of depression that may have important implications for treatment."

Ultimately, the researchers want to develop clinical tools to help predict if a first episode of depression is likely to persist as a disorder or progress into bipolar disorder. "Genetic data won't ever replace clinical insight, but it might be a useful addition to clinical models," said Coleman.
-end-
Notes for editors

The article is "The genetics of the mood disorder spectrum: genome-wide association analyses of over 185,000 cases and 439,000 controls ," by Jonathan R.I. Coleman, Héléna A. Gaspar, Julien Bryois, Bipolar Disorder Working Group of the Psychiatric Genomics Consortium, Major Depressive Disorder Working Group of the Psychiatric Genomics Consortium, Gerome Breen. (https://doi.org/10.1016/j.biopsych.2019.10.015). It appears inBiological Psychiatry, published by Elsevier.

Copies of this paper are available to credentialed journalists upon request; please contact Rhiannon Bugno at Biol.Psych@sobp.org. Journalists wishing to interview the authors may contact Gerome Breen at gerome.breen@gmail.com or +44 20 784 804 09 or Jonathan Coleman at jonathan.coleman@kcl.ac.uk, or +44 20 784 808 56.

The authors' affiliations and disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, MD, is Chairman of the Department of Psychiatry at the Yale University School of Medicine, Chief of Psychiatry at Yale-New Haven Hospital, and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.

AboutBiological Psychiatry

Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.

The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.

Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 7th out of 146 Psychiatry titles and 12th out of 267 Neurosciences titles in the Journal Citations Reports® published by Clarivate Analytics. The 2018 Impact Factor score for Biological Psychiatry is 11.501. http://www.sobp.org/journal

About Elsevier

Elsevier is a global information analytics business that helps scientists and clinicians to find new answers, reshape human knowledge, and tackle the most urgent human crises. For 140 years, we have partnered with the research world to curate and verify scientific knowledge. Today, we're committed to bringing that rigor to a new generation of platforms. Elsevier provides digital solutions and tools in the areas of strategic research management, R&D performance, clinical decision support, and professional education; including ScienceDirect, Scopus, SciVal, ClinicalKey and Sherpath. Elsevier publishes over 2,500 digitized journals, including The Lancet and Cell, 39,000 e-book titles and many iconic reference works, including Gray's Anatomy. Elsevier is part of RELX, a global provider of information-based analytics and decision tools for professional and business customers. http://www.elsevier.com

Media contact
Rhiannon Bugno, Editorial Office
Biological Psychiatry
+1 214 648 0880
Biol.Psych@sobp.org



Elsevier

Related Depression Articles from Brightsurf:

Children with social anxiety, maternal history of depression more likely to develop depression
Although researchers have known for decades that depression runs in families, new research from Binghamton University, State University of New York, suggests that children suffering from social anxiety may be at particular risk for depression in the future.

Depression and use of marijuana among US adults
This study examined the association of depression with cannabis use among US adults and the trends for this association from 2005 to 2016.

Maternal depression increases odds of depression in offspring, study shows
Depression in mothers during and after pregnancy increased the odds of depression in offspring during adolescence and adulthood by 70%.

Targeting depression: Researchers ID symptom-specific targets for treatment of depression
For the first time, physician-scientists at Beth Israel Deaconess Medical Center have identified two clusters of depressive symptoms that responded to two distinct neuroanatomical treatment targets in patients who underwent transcranial magnetic brain stimulation (TMS) for treatment of depression.

A biological mechanism for depression
Researchers report that in depressed individuals there are increased amounts of an unmodified structural protein, called tubulin, in lipid rafts compared with non-depressed individuals.

Depression in adults who are overweight or obese
In an analysis of primary care records of 519,513 UK adults who were overweight or obese between 2000-2016 and followed up until 2019, the incidence of new cases of depression was 92 per 10,000 people per year.

Why stress doesn't always cause depression
Rats susceptible to anhedonia, a core symptom of depression, possess more serotonin neurons after being exposed to chronic stress, but the effect can be reversed through amygdala activation, according to new research in JNeurosci.

Which comes first: Smartphone dependency or depression?
New research suggests a person's reliance on his or her smartphone predicts greater loneliness and depressive symptoms, as opposed to the other way around.

Depression breakthrough
Major depressive disorder -- referred to colloquially as the 'black dog' -- has been identified as a genetic cause for 20 distinct diseases, providing vital information to help detect and manage high rates of physical illnesses in people diagnosed with depression.

CPAP provides relief from depression
Researchers have found that continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea (OSA) can improve depression symptoms in patients suffering from cardiovascular diseases.

Read More: Depression News and Depression Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.